DE19849790A1 - Scraper for a friction element of a vehicle brake and brake lining equipped with it - Google Patents

Abstract

In order to avoid the reduction in the coefficient of friction between a friction element of a vehicle brake and an element to be braked due to moisture in the components mentioned, it is known to provide materials that are as insensitive to moisture as possible for the friction elements or a special geometric configuration of the same. The new scraper and the brake lining equipped with it are said to increase the coefficient of friction between a friction element of a vehicle brake and an element to be braked, even in damp, wet and cold weather conditions, with less crack formation and less wear. DOLLAR A For this purpose it is provided that the wiper (6, 6 ', 6' ', 6' '') according to the invention for a friction element (1) of a vehicle brake, in particular a rail vehicle brake, consists of at least one web (9, 9 ', 9' ', 9' '', 21). Slats (11) can protrude from this, so that chambers (10, 19) are formed. DOLLAR A With the wiper according to the invention it is not only possible to achieve high coefficients of friction, but also to retrofit existing friction elements.

Description

The present invention relates to a wiper for a driving friction element tool brake, in particular a rail vehicle brake, according to claim 1, and a brake lining for a friction brake of a vehicle, in particular Rail vehicle, according to claim 10.

The coefficient of friction between a friction element of a vehicle brake and an ab braking element depends in particular on the moisture of the construction mentioned divide. The friction element consists of a porous material, the weather conditionally absorbs water. As a result, the physical coefficient of friction between Rei Exercise element and component to be braked compared to the coefficient of friction dry construction parts reduced. In the case of a rail vehicle brake, this means that the friction value between the brake pad (friction element) and the brake disc (brake to be braked Element) is reduced.

The coefficient of friction is further reduced if between the friction element and the component to be braked hits a so-called aquaplaning effect, which leads to floating of the friction element during the braking process can result. This happens especially at low surface pressures and leads to a physi coefficient of friction down to almost zero.

Both the water absorption of the friction element material and the aqua planing effect can lead to inadmissible braking distance extensions.

To avoid the above-mentioned problems, it is known to be insensitive to moisture as much as possible to provide materials for the friction elements. However, today there is  paradoxical situation that materials for friction elements with good friction values and good contact pattern are inadmissibly sensitive to moisture while dry Friction elements with rather unfavorable wear values and friction properties or with a tendency to form hot spots in the dry state as a result of bad contact pattern are rather insensitive to moisture. Therefore, as brake pads friction elements intended for rail vehicles according to Union regulations International des Chemins de Fer (UIC) tested for a lack Uncover friction coefficient behavior under moisture and / or wetness. However, this is with a considerable technical and organizational effort.

It is also known that the wetness problem is caused by a special geometry to meet the friction element. So is in DE 89 05 731 U1 a brake pad described for partial lining disc brakes of rail vehicles in particular, which is formed in one or more parts and has about kidney shape and if necessary, fastened with a dovetail guide on a rubber support is, the existing at both ends of a brake pad in several straight partial areas are divided, which are over the entire Engagement area of the brake pad and which extend an angle of less than Form 90 ° to the friction surface of the brake disc. The known brake pad has the Disadvantage that a friction-increasing effect only with complete conversion of the Rail vehicle brake is achieved. Retrofitting already existing brake pads with a friction-increasing device is therefore not possible.

From DE-OS 14 30 869 a motor vehicle disc brake is known in which over the friction surfaces a larger number of water drainage holes or The like is distributed approximately evenly. Here too is an afterthought It is not possible to equip existing brake pads. Further penetrate the Water drainage holes completely rub the surface so that it tends to crack and is subject to increased wear. In addition, the friction surface is lost.

Finally, in EP-0 443 360 B1 there is a brake pad for partial pad disc brakes described with a brake disc, in particular of rail vehicles, in which  on the opposite side and for contact with the brake disc the front of the disc brake provided water drainage devices are provided, for which the brake pad with a number of each other one Distance, from the front of the brake pad to its Continuously extending back, for receiving and removing friction-preventing dirt such as water, ice, abrasion or the like suitable openings are provided. This brake pad is characterized by it from the fact that it is formed in one or more parts and approximately in the shape of an annular segment and that at least on the front of the brake pad of any circular lines 30% each cut at least one of the intended openings or touch, and a maximum degree of coverage of the openings of 150% exists, in which every conceivable circular ring line touches at least one opening or cuts so that everyone enters on any circular ring line Drops of water is supplied to an opening, or that the area of the Openings of the opening on the front of the brake pad to the whole Front surface including the area of the openings of the openings in a relation between 2: 100 (minimum) and 35: 100 (maximum), or that on any circular ring line per 150 mm on the front of the brake pad Circular line length at least one opening and a maximum of five openings cuts or touches.

The openings penetrate the friction body completely, so that this too Cracking tends and is subject to increased wear. Another disadvantage is that a friction-increasing effect is only achieved if the Rail vehicle a completely new brake pad is used. An afterthought Equipment of existing brake pads is therefore also in this device not possible.

In contrast, the invention has for its object a device for Increasing the coefficient of friction between a friction element of a vehicle brake and an element to be braked even when it is damp, wet or cold to create the same weather, which leads to less cracking and less Wear of the friction element leads.  

This task is accomplished by a wiper for a friction element Vehicle brake, in particular a rail vehicle brake, consisting of at least one bridge.

The scraper according to the invention can advantageously be used with already known ones Friction elements, especially brake pads according to UIC regulations or Annular sector brake pads are used without their cracking behavior or wear changes. So it is possible to already in the wiper according to the invention existing grooves, in particular press grooves, a brake pad or between two To use partial pads of a brake pad. The invention Wipers attached positively and / or non-positively and / or frictionally, especially by pressing. Alternatively or cumulatively, the scraper can be connected to a Be glued outside of the friction element or in a groove.

The scraper according to the invention also has the advantage that it corresponding installation in a friction element in the form of a brake lining in both directions of rotation of the element to be braked, in particular one Disc brake, is effective. This does not only apply immediately after installing the scraper according to the invention in the friction element, but also in already advanced wear. The scraper takes effect until the Wear limit of the friction element has been reached. It will decelerated element neither impaired in its effect, nor damaged. This especially because the scraper with less pressure on the element to be braked rests.

The scraper according to the invention can advantageously in a way Retrofitting to be attached to the friction elements.

Because of its simple construction, the wiper according to the invention can be made from Bar profiles are manufactured. It is advantageous for everyone Brake pad sizes suitable.  

The scraper according to the invention can advantageously spring elements have, which lie against the grooves in the friction element, so that the scraper according to the invention is under tension.

Advantageous developments of the invention result from the features of Subclaims.

Another solution to the above problem is the one described above Wiper not to be provided as a separate component, but already on one Brake lining for a friction brake of a vehicle, in particular Rail vehicle to be able to attach integratively. The advantages described above can also be found with this solution.

The scraper is due to its accommodation in a groove of the invention Brake pads against external influences such as improper handling, Protected against falling rocks or the like. It is advantageously long and can be used safely.

Further features and advantages of the scraper according to the invention and the Brake pads according to the invention can be seen in the drawing in which

Fig. 1 a circular ring sector brake lining according to the invention with two scrapers,

Fig. 2 shows a the, stripper according to the invention shown in Fig. 1 in a perspective view;

Fig an alternative embodiment of the, stripper. 3 according to the invention used in a brake lining,

Fig. 4 shows a further alternative embodiment of the, stripper used in a brake lining according to the invention,

Fig. 5 shows a further alternative embodiment of the scraper according to the invention, used in a brake lining,

Fig. 6 shows a further alternative embodiment of the scraper according to the invention, used in a brake lining,

Fig. 7 shows a further alternative embodiment of the, stripper used in a brake lining according to the invention,

Fig. 8 shows a further alternative embodiment of the scraper according to the invention, used in a brake lining,

Fig. 9 shows a further alternative embodiment of the scraper according to the invention, used in a brake pad, and

FIG. 10 shows a part of the stripper shown in FIG. 8, cut in a longitudinal view.

In Fig. 1, a friction element 1 in the form of an annular sector brake pad is shown. The friction element 1 is part of a disc brake system for a rail vehicle, which is not shown in detail. For braking of the rail vehicle or for holding the rail vehicle in the braked state, the friction element 1 is brought against a braked member 2 in system. In the example shown here, the element 2 to be braked, which is only partially shown with a broken line, is a brake disc. There is a water front 3 between the friction element 1 and the element 2 to be braked, the direction of flow of which is shown by way of example by means of arrows 4 in FIG. 1. The water front 3 can consist of rain water, dew, ice, melt water or the like and contain abrasion and other friction-preventing soiling.

The friction element 1 has two mutually spaced grooves 5 which extend radially across its width. A wiper 6 is inserted into each groove 5 . During a braking operation, the water front 3 flows in the direction 4 up to the upper scraper 6 shown in FIG. 1. The water front 3 is detected and derived by the stripper 6 , which extends over the entire width of the friction element 1 and essentially transversely to the flow direction 4 , until the water front 3 leaves the space between the friction element 1 and the element 2 to be braked in the outflow direction 7 . The part of the friction element 1 located below the upper scraper 6 is thus free of the water front 3 and the contaminants contained therein.

In the event that not all of the water following the water front 3 is discharged from the upper scraper 6 in FIG. 1 in the outflow direction 7 , a second scraper 6, which is lower in FIG. 1, is provided. This is located in a second groove 5 , which also extends over the entire width of the friction element 1 and essentially transversely to the water front 3 . Here, too, the water front 3 is detected, since the stripper 6 extends radially over the entire width of the friction element 1 , and is discharged in the outflow direction 8 due to gravity.

The friction element 1 shown in FIG. 1 is constructed symmetrically with respect to its bisecting H. The upper scraper 6 in FIG. 1 is oriented with respect to the bisector H at an angle α not equal to 0 °, in this case 20 °. The lower scraper in FIG. 1 is also aligned with an angle β not equal to 0 ° with respect to the bisector H, the angle β being smaller than the angle α in the example shown here. In a preferred embodiment, the angles α and β are equal. In general, the center bisector H coincides with a radial of the brake disc as the element 2 to be braked.

The scraper 6 shown in FIG. 1 is shown again in a perspective view in FIG. 2. In this example, the wiper 6 is designed as a web 9 which has a rectangular cross section. The web 9 consists of a rubber or a thermoset-like material and can be produced, for example, by injection molding or extrusion. Of course, other cross-sectional shapes and / or materials, such as foam metal, can also be provided.

In Fig. 3 an alternative embodiment of the scraper 6 , which is located in the friction element 1, is shown in a sectional view. The web 9 is in this case V-shaped in profile. The legs of the web 9 lie against the groove 5 in such a way that a chamber 10 is formed between them. In this chamber 10 , the water detected by the stripper 6 can be drained off, as has already been explained with reference to FIG. 1. The V-shaped web 9 can also be made of a rubber or a thermosetting material. Due to the elasticity of these materials, the stripper 6 shown in FIG. 3 is pretensioned in the groove 5 , so that it cannot fall out of the friction element 1 .

In FIG. 4 a further embodiment of the scraper according to the invention. The scraper 6 'shown here also has a web 9 ' which, however, has a reduced width compared to the web 9 shown in FIG. 2. Six lamellae 11 protrude from the web 9 'in the manner of a blind, which extend over the entire length of the web 9 ', and thus the entire width of the friction element 1 . The four left lamellae 11 shown in FIG. 4 lie against the upper wall 12 of the groove 5 . The two right slats 11 shown in FIG. 4, however, have free ends. Due to the slanted position of the slats 11 relative to the element 2 to be braked (not shown here), two of them are always on the surface of the element to be braked. Here, too, a multiplicity of chambers 10 are formed by the web 9 ′, the slats 11 , the wall 12 and the element 2 to be braked.

The web 9 'has six holding projections 13 on the side opposite the slats 11 , which abut against the lower wall 14 of the groove 5 . The holding projections 13 are tooth-shaped and prevent the stripper 6 ′ from falling out of the friction element 1 , also because of the elasticity of the slats 11 made of a rubber or thermoset-like material. The embodiment of the scraper 6 'according to the invention shown here can have a web 9 ' made of metal or plastic. Fig. 4 shows that the holding projections 13 can be made significantly smaller than the slats 11 .

Fig. 5 is also a scraper 6 '', the web having plates 11. However, in contrast to the stripper 6 shown in FIG. 4, these are provided on both sides of the web 9 ″. Here too, the web 9 ″, the slats 11 , the upper wall 12 and the element to be braked form 2 chambers 10 , which are located in FIG. 5 above the web 9 ″.

In contrast to the embodiment shown in FIG. 4, the wiper 6 ″ shown in FIG. 5 also has chambers 15 below the web 9 ″, which are formed by the web 9 ″, the lower wall 14 and the element 2 to be braked become.

When the element 2 to be braked shown in FIG. 5 rotates downward in the direction of movement 16 , the water front 3 flows into the chamber 10 along the direction of flow 4 . From this, the water, as shown in Fig. 1, is discharged due to gravity, namely in the outflow direction 7 if the scraper 6 '' shown in Fig. 5 is the upper scraper 6 shown in Fig. 1, or in the outflow direction 8 if the scraper 6 ″ shown in FIG. 5 is the lower scraper 6 shown in FIG. 1.

If the direction of movement of the element 2 to be braked changes in the direction of movement 17 , a further water front 18 flows into the chamber 19 , which can be found in the space below the web 9 ″. The water also flows out of the chamber 19 as previously described.

Thus may be referred to as double-acting scraper 6 in Fig. 2, Fig. 3 and stripper 6 5 shown Fig. And 6 '', because they can strip the water in both directions of movement 16 and 17 of the element to be braked 2. The scraper 6 'shown in FIG. 4, on the other hand, is a single-acting scraper 6 , since it drains off the water flowing in at the top in FIG. 4. By inserting the scraper 6 ′ shown in FIG. 4 into the upper groove 5 shown in FIG. 1, the water flowing in the direction of flow 4 is drained off. In order to be able to discharge water flowing from bottom to top in FIG. 1, a scraper 6 'shown in FIG. 4 is rotated such that the chambers 10 open in the direction of the corresponding flow. Thus, the safe function of the scraper 6 according to the invention is also achieved with a single-acting scraper 6 '. Of course, can also be designed as a double-acting scraper 6 scraper 6 '' according to Fig. 1 are inserted in the friction element 1.

Clogging of the chambers 10 and 19 caused by dirt, abrasion or the like is not to be feared since the water flowing into them has a rinsing effect. It should also be taken into account that the individual chambers 10 and 19 are sealed from one another.

Friction elements 1 used for braking purposes are subject to heavy wear. A corresponding wear limit dimension 20 for a disc brake system used in rail vehicles is shown in FIG. 5 with reference number 20 . The wear on the friction element 1 designed as a brake disc progresses from right to left in FIG. 5. It is clear that also in case of wear of the friction element 1 6 '', is retained as well as the web 9 ', the function of the stripper' and protruding from it plates 11 wear out, wherein in Fig. 5 extending from right to left always new chambers 10 and 19 are opened again. The latter is also the case in FIGS. 3 and 4 shown wipers 6 and 6 '.

In Fig. 6, another embodiment is shown of a scraper according to the invention. The scraper 6 '''has a right-angled web 9 ''', one leg of the web 9 '''resting against the lower wall 14 of the groove 5 and its other leg perpendicular to the element 2 to be braked Side is provided and extends to the upper wall 12 of the groove 5 . Lamellae 11 protrude from both legs of the web 9 '''in such a way that a wiper 6 acting on one side is produced. This also has a chamber 10 through which water flowing in in the direction of flow 4 can be drained off.

As can be seen from Fig. 6, the groove 5 need not be substantially wedge-shaped. Rather, a groove 5 with a rectangular cross section can also be provided in the friction element.

Fig. 7 shows another embodiment of a scraper 6 according to the invention. The scraper 6 '''is located in a groove 5 which is rectangular in cross section, a web 9 ''' now being provided, which is designed in a zigzag shape and bears against the lower wall 14 of the groove 5 . The wiper 6 '''further has a web 21 which is symmetrical with the web 9 ''' and which bears against the upper wall 12 of the groove 5 . The zigzag shape of the two webs 9 '''and 21 likewise form a number of chambers 10 through which water flowing in in the direction of flow 4 and in the direction of flow 18 can be drained off.

In FIG. 8, another embodiment of the stripper 6 according to the invention. Here, the web 9 '''of the stripper 6 ''' is designed as a U-profile, from which limbs 11, which bear against the upper wall 12 and the lower wall 14 of the groove 5, protrude in such a way that a number of chambers 10 are again formed become.

The wipers 6 '''shown in FIGS. 6 to 8 also act on both sides. For this purpose, the lamellae 11 or webs 9 and 21 are arranged inclined relative to the side of the element 2 to be braked against which the friction element 1 comes to rest.

Finally, FIG. 9 shows a last embodiment of the wiper 6 according to the invention. The web 9 '''' of the stripper 6 '''' is also essentially U-shaped in this case. However, in this embodiment, the legs of the stripper 6 '''' are inclined relative to the center bisector M such that the distance between the free ends of the stripper 6 '''', which are shown on the right in FIG. 9, is smaller than that Width of the web 9 '''' on the side of the scraper 6 '''' opposite the element to be braked (not shown). Here, too, the legs of the stripper 6 ″ ″ lie directly against the upper wall 12 and the lower wall 14 of the friction element 1 . The free ends of the two legs protrude a little beyond the groove 5 .

Between the web 9 '''' and the bottom of the groove 5 shown in Fig. 9 a Fe derelement 22 is provided. The wiper 6 '''' is biased against the upper wall 12 and the lower wall 14 of the groove 5 by the spring element. The spring element 22 acting as a compression spring can be used as a separate component between the groove and the wiper 6 ''''.

FIG. 10 shows a part of the wiper 6 '''' shown in FIG. 9 in a longitudinal view. In the exemplary embodiment shown here, not only one spring element 22 , but also further spring elements 22 ′ and 22 ″ are provided, all of which can have the same dimensions or different dimensions. The distance between the individual spring elements 22 , 22 'and 22 ''can be provided uniformly or unevenly over the length of the friction element 1 .

The spring elements 22 , 22 'and 22 ''are designed as tongues which rest against the bottom of the groove 5 by the web 9 ''''. The spring elements 22 , 22 'and 22 ''are advantageously partially pushed out of the web 9 ''''so that they are integrally formed on the web 9 ''''. Of course, other configurations of the spring elements 22 , 22 'and 22 ''are possible, in particular in the form of beads (not shown) which rest against the bottom of the groove 5 by the web 9 ''''.

As already explained above, the wipers 6 , 6 ', 6 '', 6 ''' and 6 '''' consist of a heat-resistant plastic or rubber. But metal is also suitable as a material for the wipers 6 , 6 ', 6 '', 6 ''' and 6 '''' according to the invention. In any case, the selected materials are those that are heat-resistant and flexible so that the webs 9 , 9 ', 9 '', 9 ''' and 9 '''' and the slats 11 against the element to be braked 2 or against the groove 5 , which advantageously ensures good contact between the wipers 6 , 6 ', 6 '', 6 ''' and 6 '''', groove 5 and the element 2 to be braked. This applies all the more if the wiper 6 , 6 ', 6 '', 6 ''' and 6 '''' is used under pre-tension, because this also means that the elastically designed webs 9 , 9 ', 9 '', 9 '''and 9 ''''as well as the fins 11 are under tension and, acting as spreading springs, prevent the stripper 6 , 6 ', 6 '', 6 '''and 6 ''''from falling out.

It is understood that the wiper according to the invention is not only used for disc brakes systems can be used, but also in block brake systems, drum braking systems or the like.  

Reference list

1

Friction element

2nd

element to be braked

3rd

Waterfront

4th

Flow direction

5

Groove

6

,

6

',

6

'',

6

'' ',

6

'''' Scraper

7

Outflow direction

8th

Outflow direction

9

,

9

',

9

'',

9

'' ',

9

'''' Footbridge

10th

chamber

11

Slats

12th

top wall

13

Retaining tabs

14

bottom wall

15

chamber

16

Direction of movement

17th

Direction of movement

18th

Flow direction

19th

chamber

20th

Wear limit

21

web

22

,

22

',

22

'' Spring element
H, M bisector
α, β angle

Claims (16)

1. Scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') for a friction element ( 1 ) of a vehicle brake, in particular a rail vehicle brake, consisting of at least one web ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ). 2. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to claim 1, characterized in that of the web ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ) protrudes at least one lamella ( 11 ). 3. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to claim 1 or 2, characterized in that the web ( 9 , 9 ', 9 '', 9 ''' , 9 '''', 21 ) has at least one holding projection ( 13 ). 4. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 1 to 3, characterized in that the web ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ) is essentially U-shaped or V-shaped in cross-section. 5. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to any one of claims 1 to 3, characterized in that the web ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ) is zigzag in cross section. 6. Wiper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 2 to 5, characterized in that the lamellae ( 11 ) on the web ( 9 , 9 ', 9th '', 9 ''', 9 '''', 21 ) are arranged symmetrically. 7. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 2 to 6, characterized in that the webs ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ) and / or the slats ( 11 ) form chambers ( 10 , 19 ). 8. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to claim 7, characterized in that the chambers ( 10 , 19 ) are separated from each other. 9. scraper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 1 to 8, characterized in that the length of the scraper ( 6 ) at least the width of the friction element ( 1 ) corresponds. 10. Wiper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 1 to 9, characterized in that at least one spring element ( 22 , 22 ', 22 '') is provided is. 11. Wiper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to claim 10, characterized in that the spring element ( 22 , 22 ', 22 '') integrally on the web ( 9th , 9 ', 9 '', 9 ''', 9 '''') is formed. 12. Brake pad for a friction brake of a vehicle, in particular rail vehicle, characterized in that a wiper ( 6 , 6 ', 6 '', 6 ''', 6 '''') according to one of claims 1 to 11 on the brake pad is appropriate. 13. Brake pad according to claim 12, characterized in that the stripper ( 6 , 6 ', 6 '', 6 ''', 6 '''') is mounted in a groove ( 5 ). 18. Brake pad according to one of claims 12 to 17, characterized in that at least one wiper ( 6 , 6 ', 6 '', 6 ''', 6 '''') with respect to the median bisector (H) of the friction element ( 1 ) is oriented at an angle (α, β) not equal to 0 °. 19. Brake pad according to one of claims 12 to 18, characterized in that between the stripper ( 6 , 6 ', 6 '', 6 ''', 6 '''') and groove ( 5 ) a spring element ( 22 , 22 ' , 22 '') is provided. 20. Brake pad according to claim 19, characterized in that the spring element ( 22 , 22 ', 22 '') integrally on the web ( 9 , 9 ', 9 '', 9 ''', 9 '''', 21 ) is trained.